192 SYSTEMATIC BOTANY. 



, a pair, and 4>vr6v), plants in which the sexes are 

 united. 



Sub-class 1. Zoosporeae, Cells capable of motion. 

 Sub-class 2. Conjugatse, Cells fixed. 



494. CLASS VI. Protophyta. First or most simple 

 class of plants (Greek Trp&To?, first, and 0vr6v). These 

 plants are the lowest vegetable organisms, and consist 

 of single cells, or strings of cells. 



Sub-class 1. Myxomycetes, Slime molds, naked pro- 

 toplasm, without regular form. 



Sub-class 2. Schizomycetes, Bacteria minute cells. 

 Sub-class 3. Cyanophycese, Green Slimes. 



495. Orders or Families succeed to the Cohorts. 

 The Natural Order is perhaps the most important of 

 all the associations. On the accuracy and distinct- 

 ness of the characters of these groups botanists have 

 bestowed the highest degree of attention, and the 

 student's progress will largely depend upon his acquaint- 

 ance with them. 



496. Orders are formed by associating together 

 those genera which have the most intimate relations 

 to each other, or to some one genus previously as- 

 sumed as the type. As species form genera, so 

 genera form Orders. In regard to extent, they differ 

 widely ; some consisting of a single genus, as, Plata- 

 naceae, while others comprehend hundreds of genera, 

 as, Compositae. For convenience in analysis, the larger 

 Orders are broken up into Sub-orders or Tribes. 



The Flowering plants of the whole world, known to botanists, have been 

 grouped under 200 Orders, 7,500 Genera, and 100,000 species. About 80,000 of 

 these species are Dicotyledons, and the remaining 20,000 are Monocotyledons. 



It is a high accomplishment in a botanist to possess an extensive ac- 

 quaintance with individual plants. The ability to determine readily the genus 

 and species to which a plant belongs depends largely upon an accurate knowl- 

 edge of the characters of the orders and tribes. 



